Maintaining a cast iron skillet (Cleaning and seasoning)

I just bought my first cast iron skillet to use to grill meats on a tabletop induction cooktop. I just used it to cook marinated chicken breast last week which turned out great. However, now I have some questions about maintaining my cast iron grill pan for many more future uses.

I am first wondering the best way to clean it. I did much research on the internet and in this forum and many people indicate that you only wash with warm water but a few say to wash with soap and water. My concern is the growth of bacteria from food even if it is cleaned with water very well. I would think soap would be important.

I am also wondering about the seasoning process. Mine is supposed to be pre-seasoned but I assume I should season myself as well. I have heard that it is possible for cast iron to rust and don't want that happening. What type of oil is used for this ?